Los Colorados (caldera)

26°05′S 68°19′W / 26.09°S 68.32°W / -26.09; -68.32[1]

Los Colorados is the name of a caldera in Chile. It is part of the Central Volcanic Zone of the Andes.[2]

The caldera has a diameter of 30 kilometres (19 mi) and was formed 9.8 million years ago within a basement consisting of Paleozoic rocks, Miocene ignimbrites and older volcanoes.[3]

The caldera is the source of the 500 cubic kilometres (120 cu mi) Los Colorados ignimbrite,[3] which was erupted 7.9-7.76 million years ago.[1] This ignimbrite is formed by highly welded dacite, is rich in pumice and has a dark pink colour. Quartz, sherds are also widespread.[2][1] This ignimbrite covers a surface area of 89.03 square kilometres (34.37 sq mi),[1] spilling into Argentina.[4] Part of the Los Colorados ignimbrite has been identified at the Laguna Amarga caldera.[1]

After the formation of the caldera, between 6.9 and 6.8 million years ago the Abra Grande, Aguas Calientes and Río Grande stratovolcanoes grew in the caldera. Lava flows from Cerro Bayo and Cordón del Azufre have invaded the northwestern sector of the caldera.[3]

The Los Colorados caldera coalesces with the Lazufre structure along the Archibarca lineament and is associated with a major fault, the Pedernales-Arizaro overthrust.[3] This fault may have favoured the formation of the Los Colorados caldera by facilitating the formation of a magma chamber.[2]

  1. ^ a b c d e Guzmán, Silvina; Grosse, Pablo; Montero-López, Carolina; Hongn, Fernando; Pilger, Rex; Petrinovic, Ivan; Seggiaro, Raúl; Aramayo, Alejandro (2014-12-01). "Spatial–temporal distribution of explosive volcanism in the 25–28°S segment of the Andean Central Volcanic Zone". Tectonophysics. 636: 170–189. Bibcode:2014Tectp.636..170G. doi:10.1016/j.tecto.2014.08.013. hdl:11336/32061.
  2. ^ a b c Naranjo, José Antonio; Villa, Víctor; Ramírez, Cristián; de Arce, Carlos Pérez. "Oligo - Holocene evolution of the southern part of the Central Andes: volcanism and tectoni" (PDF). Archived from the original (PDF) on 2017-04-06. Retrieved 29 December 2016.
  3. ^ a b c d Naranjo, J. A.; Villa, V.; Ramírez, C.; Pérez de Arce, C. (2014-12-01). "Miocene to Recent geological evolution of the Lazufre segment in the Andean volcanic arc". AGU Fall Meeting Abstracts. 31: V31E–4796. Bibcode:2014AGUFM.V31E4796N.
  4. ^ Sergio, Gamonal (2015-08-20). Volcanic stratigraphy and epithermal mineralization of the La Coipa district, Maricunga belt, Chile (Thesis). doi:10.14288/1.0135534.